In an inkjet printing device, in order to get graphics and text printed or overprinted accurately at certain fixed positions, printing positioning accuracy of the inkjet printing device is highly required. The conventional method solving the problem of printing accuracy or overprinting accuracy is to adjust the inkjet unit to locate above the printing or overprinting area, and then to adjust and control the corresponding nozzles of the printing head to print. In this way, graphics and text could be printed or overprinted accurately at certain fixed positions.
The inventors of the present invention find that, as the printing positioning is achieved by adjusting and controlling the nozzles of the printing head, some deficiencies may be resulted, for example, the utilization ratio of the nozzles of the printing heads may be reduced, the printing format may be affected, and the adjustment may cost more time, etc.